I was using my ATI Radeon 3450 on my Optiplex 760 just fine on a regular basis, but today it stopped working.

I was using my ATI Radeon 3450 on my Optiplex 760 just fine on a regular basis, but today I went to power it on and the power light is orange, lights 123 light up, when I removed it to use onboard graphics, it worked, but I still want to use my graphics card...